1. Field of the Invention
The invention is as described herein and shown in the accompanying drawings is for a rail welding apparatus incorporating a railroad rail restraining device, weld containment device, robotic welding head and weld delivery unit having improved rail restraining characteristics, improved weld supporting properties and being compact, lightweight and economical for greater utility. The restraining device enables the positioning of rail ends of either long prewelded rails, special rail sections for appliances such as in frogs or turn-outs or switches, existing rails in need of repair, or a combination of these. Because of the high strength, improved geometry and design, the device can be utilized in the gas-arc welding of highly restricted clearance rail splices or joints, such as in welding a length of rail to a turn-out assembly. The precision of the apparatus disclosed herein is believed to make gas-arc welding of rails in the field feasible, while the disclosures in some of the patents identified above were better suited to laboratory use and were unable to reach success in the field.
2. Description of Related Art
In the prior art, there are three main ways to weld railroad track. These include aluminothermic welding (U.S. Pat. Nos. 5,215,139 and 5,306,361), flash-butt welding (U.S. Pat. Nos. 4,929,816; 5,270,514; and 5,469,791); and gas-arc welding (U.S. Pat. No. 5,605,283). These all have certain advantages and disadvantages. Aluminothermic welding has low equipment requirements, is economical to perform but produces welds of less strength than the other methods. Flash butt welding uses complex equipment but produces high strength welds, however it is difficult to use to join rails in the field, and results in a loss of rail length, which can cause difficulties. Gas-arc welding requires precise alignment and a considerable length of time to perform a weld of sufficient strength, heretofore also requiring equipment of considerable size, complexity and cost. Gas-arc welding has been taught in U.S. Pat. Nos. 5,605,283, 5,773,779 and 5,877,468 as well as other patents based upon those disclosures. The disclosures in U.S. Pat. Nos. 5,605,283, 5,773,779 and 5,877,468 are incorporated by reference as if fully set forth herein. U.S. Pat. No. 5,605,283, shares common ownership with the instant application. The invention enables the use of gas-arc welding with greater ease and lower cost and with commercial viability where the teachings in certain of the above patents were unable to obtain repeatable results in actual use in the field.
The rail restraining device, weld containment device, robotic welding head and weld delivery unit of the invention needs to handle rail sections often as long as or longer than 1800 feet, aligning rail ends precisely for welding, yet can be made sufficiently compact to be incorporated on a transport device such as a hi-rail equipped over-the-road truck or shipping container on a chassis or car having economy or equipment for over-the-road use while being sufficiently small sized itself to fit in the space available to weld rails even in switches or turnouts or in frogs where the weld joint is separated from the adjacent rail portion by as little as about 7xe2x80x3 to 11xe2x80x3.
The rail restraining device or devices and weld delivery unit take up a sufficiently small volume of space that the truck can be fitted with room for the welder itself; control devices; boom; generator; induction heater; and gas bottles; as well as one or more portable welding robots.